This invention relates in general to packaging and more particularly to a container for foods and other products which is constructed in a manner to provide visual evidence that the container has been opened.
Cottage cheese, sour cream, yogurt, ice cream and other food products are normally packaged in relatively inexpensive "tub" type containers. These containers are typically formed from coated paperboard or injection molded or thermoformed thermoplastic materials such as polyethylene or polystyrene. In order to prolong the shelf life of the product, the container is provided with a tightly fitting lid which mechanically interlocks with the rim of the container. Removal of the lid permits access to the container contents and the mechanical interlock permits resealing of the container by simply pressing the lid back onto the container.
One problem with conventional food containers of this type is that the lid can be easily removed and replaced while the container is on the store shelf without providing a visual indication of such removal and replacement. Product tampering may then take place and a potential purchaser would have no way to determine upon examination of the container that tampering of the contents has occurred.
In an effort to combat the possibility of tampering with the contents of food containers, the packaging industry has attempted to make available containers which are either tamper-proof or tamper evident. Although tamper evident containers can be opened while still on the shelf in a store, the fact that they have been opened is evidenced by an easily visible indicator which alerts the public to the fact that tampering has occurred.
One particularly satisfactory type of tamper evident container is set forth in U.S. Pat. No. 4,643,329 to Mobberley et al. Mobberley discloses a container having a plastic disk insert which is fitted on top of a conventional container lid. The disk is wedged tightly in place and is of sufficient rigidity to prevent release of interlocking portions of the lid and the container. When the lid is to be removed by the consumer, the disk has a frangible center portion which is broken away to permit removal of the remaining annular ring. While this type of construction is particularly effective to provide visual evidence of container tampering, the disk covers the entire lid area and prevents the lid from being used to display product information at the point of sale.